Packaging

ABSTRACT

Packaging comprises a loudspeaker which has a board component that forms a part of the packaging and acts as a distributed mode bending wave acoustic radiator. A transducer is mounted wholly and exclusively on the radiator to vibrate it and cause it to resonate.

This application is a continuation-in-part of application Ser. No.08/707,012, filed Sep. 3, 1996 now U.S. Pat. No. 6,332,029.

DESCRIPTION Technical Field

The invention relates to packaging and more particularly to packagingincorporating loudspeakers.

BACKGROUND ART

It is known from GB-A-2262861 to suggest a panel-form loudspeakercomprising:

a resonant multi-mode radiator element being a unitary sandwich panelformed of two skins of material with a spacing core of transversecellular construction, wherein the panel is such as to have ratio ofbending stiffness (B), in all orientations, to the cube power of panelmass per unit surface area (μ) of at least 10;

a mounting means which supports the panel or attaches to it a supportingbody, in a free undamped manner;

and an electro-mechanical drive means coupled to the panel which servesto excite a multi-modal resonance in the radiator panel in response toan electrical input within a working frequency band for the loudspeaker.

U.S. Pat. No. 4,607,747 of STEINER discloses packaging comprising meansfor generating a signal or melody when opening the packaging. Aresiliently mounted signal generator is disclosed.

DISCLOSURE OF INVENTION

Embodiments of the present invention use members of nature, structureand configuration achievable generally and/or specifically byimplementing teachings of our parent application Ser. No. 08/707,012.Such members thus have capability to sustain and propagate inputvibrational energy by bending waves in operative area(s) extendingtransversely of thickness often but not necessarily to edges of themember(s); are configured with or without anisotropy of bendingstiffness to have resonant mode vibration components distributed oversaid area(s) beneficially for acoustic coupling with ambient air; andhave predetermined preferential locations or sites within said area fortransducer means, particularly operationally active or moving part(s)thereof effective in relation to acoustic vibrational activity in saidarea(s) and signals, usually electrical, corresponding to acousticcontent of such vibrational activity. Uses are envisaged in parentapplication Ser. No. 08/707,012 for such members as or in “passive”acoustic devices without transducer means, such as for reverberation orfor acoustic filtering or for acoustically “voicing” a space or room;and as or in “active” acoustic devices with transducer means, such as ina remarkably wide range of sources of sound or loudspeakers whensupplied with input signals to be converted to said sound, or in such asmicrophones when exposed to sound to be converted into other signals.

This invention is particularly concerned with packaging incorporatingacoustic devices e.g. in the form of loudspeakers. The term ‘packaging’is intended to encompass containers generally whether or not they aredisposable.

Members as above are herein called distributed mode radiators and areintended to be characterised as in the above parent application and/orotherwise as specifically provided herein.

The invention is packaging comprising a loudspeaker, characterised by aboard component forming a part of the packaging and acting as a memberhaving capability to sustain and propagate input vibrational energy bybending waves in at least one operative area extending transversely ofthickness to have resonant mode vibration components distributed oversaid at least one area and have predetermined preferential locations orsites within said area for transducer means and having a transducermounted wholly and exclusively on said member at one of said locationsor sites to vibrate the member to cause it to resonate forming anacoustic radiator which provides an acoustic output when resonating. Themember may comprise a cellular core sandwiched between skin layers. Themember may comprise a core of foamed plastics sandwiched between sheetsof craft board. The transducer may be a piezo-electric bender, and thebender may be crystalline. The member may form one side of a box. Thebox may have a lid, and means associated with the lid for triggeringactuation of the transducer on movement of the lid relative to the box.The packaging may comprise a signal generator, an amplifier and anelectric battery to drive the transducer.

BRIEF DESCRIPTION OF DRAWINGS

The invention is diagrammatically illustrated, by way of example, in theaccompanying drawings, in which:

FIG. 1 is a diagram showing a distributed-mode loudspeaker as describedand claimed in our parent application Ser. No. 08/707,012;

FIG. 2a is a partial section on the line A—A of FIG. 1;

FIG. 2b is an enlarged cross-section through a distributed mode radiatorof the kind shown in FIG. 2a and showing two alternative constructions;

FIG. 3 is a perspective diagram of an embodiment of packaging, and

FIG. 4 is a perspective view of a transducer.

BEST MODES FOR CARRYING OUT THE INVENTION

Referring to FIG. 1 of the drawings, there is shown a panel-formloudspeaker (81) of the kind described and claimed in our parentapplication Ser. No. 08/707,012 comprising a rectangular frame (1)carrying a resilient suspension (3) round its inner periphery whichsupports a distributed mode sound radiating panel (2). A transducer (9)e.g. as described in detail with reference to our parent U.S.application Ser. Nos. 09/011,773, 09/011,770 and 09/011,831 is mountedwholly and exclusively on or in the panel (2) at a predeterminedlocation defined by dimensions x and y, the position of which locationis calculated as described in our parent application Ser. No. 08/707,012to launch bending waves into the panel to cause the panel to resonate toradiate an acoustic output.

The transducer (9) is driven by a signal amplifier (10), e.g. an audioamplifier, connected to the transducer by conductors (28). Amplifierloading and power requirements can be entirely normal, similar toconventional cone type speakers, sensitivity being of the order of 86-88dB/watt under room loaded conditions. Amplifier load impedance islargely resistive at 6 ohms, power handling 20-80 watts. Where the panelcore and/or skins are of metal, they may be made to act as a heat sinkfor the transducer to remove heat from the motor coil of the transducerand thus improve power handling.

FIGS. 2a and 2 b are partial typical cross-sections through theloudspeaker (81) of FIG. 1. FIG. 2a shows that the frame (1), surround(3) and panel (2) are connected together by respective adhesive-bondedjoints (20). Suitable materials for the frame include lightweightframing, e.g. picture framing of extruded metal e.g. aluminium alloy orplastics. Suitable surround materials include resilient materials suchas foam rubber and foam plastics. Suitable adhesives for the joints (20)include epoxy, acrylic and cyano-acrylate etc. adhesives.

FIG. 2b illustrates, to an enlarged scale, that the panel (2) is a rigidlightweight panel having a core (22) e.g. of a rigid plastics foam (97)e.g. cross linked polyvinylchloride or a cellular matrix (98) i.e. ahoneycomb matrix of metal foil, plastics or the like, with the cellsextending transversely to the plane of the panel, and enclosed byopposed skins (21) e.g. of paper, card, plastics or metal foil or sheet.Where the skins are of plastics, they may be reinforced with fibres e.g.of carbon, glass, Kevlar (RTM) or the like in a manner known per se toincrease their modulus.

Envisaged skin layer materials and reinforcements thus include carbon,glass, Kevlar (RTM), Nomex (RTM) i.e. aramid etc. fibres in various laysand weaves, as well as paper, bonded paper laminates, melamine, andvarious synthetic plastics films of high modulus, such as Mylar (RTM),Kaptan (RTM), polycarbonate, phenolic, polyester or related plastics,and fibre reinforced plastics, etc. and metal sheet or foil.Investigation of the Vectra grade of liquid crystal polymerthermoplastics shows that they may be useful for the injection mouldingof ultra thin skins or shells of smaller size, say up to around 30 cmdiameter. This material self forms an orientated crystal structure inthe direction of injection, a preferred orientation for the goodpropagation of treble energy from the driving point to the panelperimeter.

Additional such moulding for this and other thermoplastics allows forthe mould tooling to carry location and registration features such asgrooves or rings for the accurate location of transducer parts e.g. themotor coil, and the magnet suspension. Additional with some weaker corematerials it is calculated that it would be advantageous to increase theskin thickness locally e.g. in an area or annulus up to 150% of thetransducer diameter, to reinforce that area and beneficially couplevibration energy into the panel. High frequency response will beimproved with the softer foam materials by this means.

Envisaged core layer materials include fabricated honeycombs orcorrugations of aluminium alloy sheet or foil, or Kevlar (RTM), Nomex(RTM), plain or bonded papers, and various synthetic plastics films, aswell as expanded or foamed plastics or pulp materials, even aerogelmetals if of suitably low density. Some suitable core layer materialseffectively exhibit usable self-skinning in their manufacture and/orotherwise have enough inherent stiffness for use without laminationbetween skin layers. A high performance cellular core material is knownunder the trade name ‘Rohacell’ which may be suitable as a radiatorpanel and which is without skins. In practical terms, the aim is for anoverall lightness and stiffness suited to a particular purpose,specifically including optimising contributions from core and skinlayers and transitions between them.

Several of the preferred formulations for the panel employ metal andmetal alloy skins, or alternatively a carbon fibre reinforcement. Bothof these, and also designs with an alloy Aerogel or metal honeycombcore, will have substantial radio frequency screening properties whichshould be important in several EMC applications. Conventional panel orcone type speakers have no inherent EMC screening capability.

In addition the preferred form of piezo and electro dynamic transducershave negligible electromagnetic radiation or stray magnet fields.Conventional speakers have a large magnetic field, up to 1 metre distantunless specific compensation counter measures are taken.

Where it is important to maintain the screening in an application,electrical connection can be made to the conductive parts of anappropriate DML panel or an electrically conductive foam or similarinterface may be used for the edge mounting.

The suspension (3) may damp the edges of the panel (2) to preventexcessive edge movement of the panel. Additionally or alternatively,further damping may be applied, e.g. as patches, bonded to the panel inselected positions to damp excessive movement to distribute resonanceequally over the panel. The patches may be of bitumen-based material, ascommonly used in conventional loudspeaker enclosures or may be of aresilient or rigid polymeric sheet material. Some materials, notablypaper and card, and some cores may be self-damping. Where desired, thedamping may be increased in the construction of the panels by employingresiliently setting, rather than rigid setting adhesives.

Effective said selective damping includes specific application to thepanel including its sheet material of means permanently associatedtherewith. Edges and corners can be particularly significant fordominant and less dispersed low frequency vibration modes of panelshereof. Edge-wise fixing of damping means can usefully lead to a panelwith its said sheet material fully framed, though their corners canoften be relatively free, say for desired extension to lower frequencyoperation. Attachment can be by adhesive or self-adhesive materials.Other forms of useful damping, particularly in terms of more subtleeffects and/or mid- and higher frequencies can be by way of suitablemass or masses affixed to the sheet material at predetermined effectivemedial localised positions of said area.

An acoustic panel as described above is bi-directional. The sound energyfrom the back is not strongly phase related to that from the front.Consequently there is the benefit of overall summation of acoustic powerin the room, sound energy of uniform frequency distribution, reducedreflective and standing wave effects and with the advantage of superiorreproduction of the natural space and ambience in the reproduced soundrecordings.

While the radiation from the acoustic panel is largely non-directional,the percentage of phase related information increases off axis. Forimproved focus for the phantom stereo image, placement of the speakers,like pictures, at the usual standing person height, confers the benefitof a moderate off-axis placement for the normally seated listeneroptimising the stereo effect. Likewise the triangular left/rightgeometry with respect to the listener provides a further angularcomponent. Good stereo is thus obtainable.

There is a further advantage for a group of listeners compared withconventional speaker reproduction. The intrinsically dispersed nature ofacoustic panel sound radiation gives it a sound volume which does notobey the inverse square law for distance for an equivalent point source.Because the intensity fall-off with distance is much less than predictedby inverse square law then consequently for off-centre and poorly placedlisteners the intensity field for the panel speaker promotes a superiorstereo effect compared to conventional speakers. This is because theoff-centre placed listener does not suffer the doubled problem due toproximity to the nearer speaker; firstly the excessive increase inloudness from the nearer speaker, and then the corresponding decrease inloudness from the further loudspeaker.

There is also the advantage of a flat, lightweight panel-form speaker,visually attractive, of good sound quality and requiring only onetransducer and no crossover for a full range sound from each paneldiaphragm.

FIG. 3 illustrates packaging incorporating the loudspeaker technology ofFIGS. 1 and 2. As shown in FIG. 3, the packaging is in the form of a box(111) having a hinged lid (139), the box, or at least part of it beingmade from a composite comprising a core of foamed plastics sandwichedbetween sheets of craft board to form a panel as shown in FIG. 2, suchthat the box comprises a rigid, lightweight distributed mode acousticradiator as described with reference to FIGS. 1 and 2.

In the present case, the rear panel (140) of the box is used to form adistributed mode radiator loudspeaker (81), although any one of thepanels making up the sides of the box would be suitable if suitablyconstructed. An alternative placement for the transducer (9) is shown indotted lines.

A piezo transducer (9) as shown in FIG. 4 is attached to the inner faceof the rear panel (140) of the box and is driven by a soundgenerator/amplifier/battery unit (112) also mounted on the rear panel.The unit (112) is controlled by a switch formed integrally with a hinge(53) by which the lid (139) is secured to the box, whereby the soundgenerator is activated when the lid is lifted.

In this arrangement the edge termination of the panel (2) is formed bythe corners of the box so that no additional frame (1) or suspension (3)of the kind shown in FIGS. 1 and 2 is required.

It will be appreciated that the packaging need not be of the shape shownin the drawing, and could, for example, be shaped according to therequirements of the contents. Thus the packaging might be shaped toenclose a compact disc or the like and may be arranged to provide anaudio preview of the contents of the compact disc or to provide otherinformation relating thereto. As another example, the packaging may forma musical box. As a further example the packaging may be arranged togive audio instructions concerning the contents.

FIG. 4 shows a transducer (9) for a distributed mode panel (2) in theform of a crystalline disc-like piezo bender (27) mounted on a disc(118), e.g. of brass, which is bonded to a face of the panel (2), e.g.by an adhesive bond (20). In operation an acoustic signal applied to thetransducer (9) via leads (28) will cause the piezo disc (27) to bend andthus locally resiliently deform the panel (2) to launch bending wavesinto the panel.

What is claimed is:
 1. Packaging comprising a loudspeaker, theloudspeaker comprising: a board component forming part of the packagingand acting as a member having selected values of certain physicalparameters which enable the member to sustain and propagate inputvibrational energy in a predetermined frequency range by a plurality ofresonant bending wave modes in at least one operative area extendingtransversely of thickness such that the frequencies of the resonantbending wave modes along at least two conceptual axes of the operativearea are interleaved and spread so that there are substantially minimalclusterings and disparities of spacings of said frequencies, the memberwhen resonating having at least one site at which the number ofvibrationally active resonance anti-nodes is relatively high; and atransducer mounted wholly and exclusively on the member at one of saidsites on the member, the transducer being capable of vibrating themember in the predetermined frequency range to couple to and excite theresonant bending wave modes in the member and cause the member toresonate and produce an acoustic output.
 2. Packaging according to claim1, wherein the member (2) comprises a cellular core (22) sandwichedbetween skin layers (21).
 3. Packaging according to claim 2, wherein themember (2) comprises a core (22) of foamed plastics (97) sandwichedbetween sheets of craft board (21).
 4. Packaging according to claim 1,wherein the transducer (9) is a piezo-electric bender.
 5. Packagingaccording to claim 4, wherein the bender (9) is crystalline. 6.Packaging according to claim 1, wherein the member (2) forms one side ofa box (111).
 7. Packaging according to claim 6, wherein the box (111)has a lid (139), and means (53) associated with the lid for triggeringactuation of the transducer (9) on movement of the lid relative to thebox.
 8. Packaging according to claim 7, comprising a signal generator,an amplifier and an electric battery (112) to drive the transducer.